The biggest obstacle to saving for retirement—probably the most important financial project we all have to undertake (unless you plan on working forever)—is the lack of money after everyday expenses. Money Under 30 shows, however, how investing as little as 50 bucks a month really adds up.

If you stashed $50 a month under your mattress for 30 years, you would end up with $18,000, but if you invested it and earned just 5 percent, you would end up with almost $40,000 – at 8 percent, that figure becomes $68,000.

You won't be able to live off your entire retirement with $68,000, but it's still $50,000 more than just socking $50 away every month without investing it. The reason, Money Under 30 explains, is the awesome power of compound interest as well as dollar cost averaging.